Lemoine and Rudik (2017) argue that it is efficient to delay reducing carbon emissions, because there is substantial inertia in the climate system. However, this conclusion rests upon misunderstanding the relevant climate physics: there is no substantial lag between CO2 emissions and warming,...

We introduce a novel methodology for adaptive targeted experiments. Our Tempered Thompson Algorithm balances the goals of maximizing the precision of treatment effect estimates and maximizing the welfare of experimental participants. A hierarchical Bayesian model allows us to adaptively target...